title: Electronic spectroscopy of the 1,3-cyclopentadiene cation (C5H6+).
abstract: The gas-phase electronic spectrum of the 1,3-cyclopentadiene radical cation (C5H6(+)) has been investigated using resonance-enhanced photodissociation of mass-selected C5H6(+)-Ar complexes in a tandem mass spectrometer. The D1((2)B1) ← D0((2)A2) band system spans the 460-620 nm range, while the D2((2)B1) ← D0((2)A2) band system appears between 320 and 370 nm. The band origins for the two systems are estimated to occur at 16,560 ± 25 and 27,808 ± 25 cm(-1), respectively. The D1 ← D0 band system exhibits a distinctive series of broad peaks, which, with the aid of molecular vibrational frequencies and geometries calculated using time-dependent density functional theory, are assigned to progressions in totally symmetric ring deformation modes. The broadening arises from the Franck-Condon activity of low-frequency out-of-plane vibrational modes, unresolved rotational contours, and possibly homogeneous lifetime broadening caused by rapid internal conversion to the ground electronic state.
authors.affiliation: School of Chemistry, The University of Melbourne , Victoria 3010, Australia.
authors.forename: Nahid
authors.initials: N
authors.lastname: Chalyavi
authors.forename: Julian A
authors.initials: JA
authors.lastname: Sanelli
authors.forename: Viktoras
authors.initials: V
authors.lastname: Dryza
authors.forename: Evan J
authors.initials: EJ
authors.lastname: Bieske